Vox Meditantis

Sarah Elizabeth Stewart’s story is one of scientific brilliance systematically undermined by institutional sexism, yet her persistence fundamentally transformed our understanding of cancer. This Mexican-American researcher proved that viruses could cause cancer—a discovery that seemed preposterous to the scientific establishment of the 1950s but would later pave the way for life-saving vaccines like the HPV vaccine that prevents cervical cancer. Her work didn’t just challenge scientific orthodoxy; it demolished it. Yet despite being nominated twice for the Nobel Prize and receiving the Federal Women’s Award from President Lyndon Johnson, Stewart remains largely forgotten. Her erasure from scientific history reveals an uncomfortable truth about how institutional discrimination shapes not just careers, but the very knowledge we celebrate.

Against All Odds: A Mexican-American Woman in Science

Born on 16th August 1905 in Tecalitlán, Jalisco, Mexico, to an American mining engineer father and Mexican mother, Stewart’s journey to scientific prominence began with displacement. The Mexican Revolution forced her family to flee to the United States when she was just five years old, yet she remained fluent in Spanish throughout her life—a testament to her refusal to abandon her heritage despite the pressures of assimilation. This early experience of being uprooted would prove formative for someone who would spend her career challenging established territories in science.

Stewart’s educational trajectory demonstrated remarkable determination. She graduated from New Mexico State University in 1927 with degrees in both science and home economics—the latter likely a concession to societal expectations about women’s roles. She earned her master’s degree in microbiology from the University of Massachusetts in 1930, then joined the National Institutes of Health (NIH) in 1935 whilst pursuing her PhD from the University of Chicago, which she completed in 1939. During this period, she published seven papers on anaerobic bacteria and helped develop a gangrene vaccine that aided soldiers during the Second World War. Here was a scientist making genuine contributions to public health, yet the establishment would soon show her just how little that mattered when she dared to challenge their assumptions.

The Institutional Wall: When Science Meets Sexism

In 1944, Stewart’s career hit a brick wall disguised as scientific scepticism. When she proposed studying the link between animal tumours and viruses, the directors of the NIH Laboratory of Microbiology and the National Cancer Institute rejected her proposal outright. Their reasoning? The idea seemed “dubious” and she lacked “appropriate qualifications”. Let that sink in: a woman with a PhD in microbiology, years of NIH experience, and published research was deemed unqualified to pursue her own scientific interests.

What qualifications did she lack, exactly? The search for an honest answer reveals the true nature of institutional discrimination. Stewart had the same credentials as her male colleagues, but she possessed something they found threatening: the audacity to challenge scientific orthodoxy whilst being a woman. The rejection wasn’t about science; it was about power, control, and the deep-seated belief that women shouldn’t be making waves in serious research.

Rather than accept this professional death sentence, Stewart made a choice that speaks volumes about her character. She resigned from the NIH and took a position as a bacteriology instructor at Georgetown University School of Medicine. This wasn’t just a career move; it was a strategic manoeuvre. Georgetown allowed her to audit medical classes, and when the school finally began admitting women in 1947, she enrolled full-time. In 1949, at the age of 43, she became the first woman to receive an MD from Georgetown University School of Medicine.

The Breakthrough: Science Vindicated

Stewart’s persistence paid off when she returned to the NIH in 1951 and began collaborating with Dr Bernice Eddy, another brilliant scientist who had been sidelined for whistleblowing about contaminated polio vaccines. Together, these two women would achieve what the scientific establishment had dismissed as impossible.

Their partnership was built on shared experience of institutional marginalisation and scientific rigour. In 1953, Stewart had confirmed Ludwig Gross’s findings about cancer transmission in mice, but the scientific community remained unconvinced. It wasn’t until 1957, when Stewart and Eddy fulfilled Koch’s postulates—the gold standard for proving causation in infectious disease—that oncologists finally took notice. They had discovered the SE (Stewart-Eddy) polyomavirus, proving definitively that viruses could cause cancer in mammals.

The impact was immediate and transformative. A 1959 Time Magazine cover story quoted the National Cancer Institute director saying, “the hottest thing in cancer research is research on viruses as possible causes of cancer”. Alan Rabson, a prominent NCI scientist, captured the moment perfectly: “The whole place just exploded after Sarah found polyoma”.

Recognition and Legacy: The Incomplete Story

Stewart’s discovery fundamentally changed cancer research, yet her recognition remained incomplete. She and Eddy were nominated twice for the Nobel Prize—a fact that underscores the significance of their work whilst highlighting how institutional biases shape even the highest honours. In 1965, President Johnson presented Stewart with the Federal Women’s Award, a recognition that, whilst meaningful, carried the implicit suggestion that her achievements were notable primarily because she was a woman.

The true measure of Stewart’s impact lies not in awards but in lives saved. Today, vaccines against human papillomavirus (HPV) prevent cervical cancer in millions of women worldwide. When Harald zur Hausen won the Nobel Prize in 2008 for discovering that HPV causes cervical cancer, he built directly on the foundation Stewart had laid decades earlier. Yet ask most people about the pioneers of cancer virology, and Stewart’s name rarely surfaces.

This erasure isn’t accidental. It reflects systematic patterns in how scientific history is written and remembered. Women’s contributions are minimised, their roles reduced to footnotes, their revolutionary insights attributed to the men who came after them. Stewart’s story challenges us to examine not just what we celebrate, but what we choose to forget.

The Uncomfortable Truth About Scientific Progress

Stewart died of cancer in 1976, having spent her final years as a professor at Georgetown University. The irony is inescapable: the woman who proved viruses cause cancer succumbed to the very disease she had dedicated her life to understanding. Yet even in death, her story offers hope. Her persistence in the face of institutional discrimination didn’t just advance scientific knowledge; it created pathways for future generations of women in science.

The challenge now is ensuring that Stewart’s legacy isn’t reduced to a feel-good story about overcoming adversity. Her experience reveals fundamental problems with how scientific institutions operate, how they distribute resources and recognition, and how they decide whose ideas deserve serious consideration. These aren’t historical curiosities; they’re ongoing issues that continue to shape scientific progress today.

Sarah Stewart proved that challenging orthodoxy can save lives. Her forgotten story reminds us that the next revolutionary discovery might come from the most unexpected source—if we’re wise enough to listen. The question isn’t whether we can afford to support unconventional ideas from marginalised scientists. It’s whether we can afford not to.

Bob Lynn | © 2025 Vox Meditantis. All rights reserved.